Electrical cable manufacture



P 7, 1955 F. A. J. DOUCHET 2,718,990

ELECTRICAL CABLE MANUFACTURE Filed July 10, 1951 Flor/ma Hn'sfick Jules IDouehed' 9- 4144014 5. Sf/ligm United States Patent" 2,718,990 ELECTRICAL CABLE MANUFACTURE .Florimond Aristide Jules Douchet, Paris, France, assignor to Societe Alsacienne .de Coustructions'Mechaniques -S. A., Paris, France Application July 10, 1951, Serial N0.'236,036 Claims priority,application France July 21 ,1950

'7 Claims. (Cl. 226-23) There exist electric cables in which the insulation between the conductorsconsists of an insulating mineral substance which is usually magnesium oxide or any other insulating substance of analogous physical characteristics.

The pulverulent nature of the insulators used in these cables leads to the placing of the assembly of conductors and the insulating material within a tubular metallic sheath 7 which can, if desired, also be used for conducting electric current.

Methods are known for packing the powdered insulating material, These methods include dehydrating-the powdered material and introducing'it into the top of a vertical sheath by joltings or repeated falls of a weight which is .subj'ectedito vertical reciprocation and which conforms to is ensured by jolts which are preferably of high frequency and whichare impressed upon the assembly formed by the sheath, the conductors and the insulating material by a vibrator, and in which a heavy mass is applied to the upper part of theinsulating material.

Preferably, the heavy weight includes a number of weights subjected to a vertical reciprocation, bearing on the insulating material and suspendedfrom one of thever- .ticalf runs of a cable the other vertical run of which supports acountcrweight in such a way as to exert on the insulating material a pressure which is practically constant whatever may be the height of the insulating material with in the sheath and to maintain the weights continuously in bearing contact with the insulating material.

The invention itself will be best understood,both as to its construction and its method of operation, from the following description of specific embodiments when read in connection with the accompanying drawings, in which:

Figure his a diagrammatic longitudinal cross-sectional view of a device constructed'in accordance with the present invention;

Figure 2 is a sectional view taken on the line IIII of Figure Z1; and

Figure 3 is a sectional view similar to that of Figure 2 for a cable having two inner conductors.

Referring now to Figs. 1 and 2, a work-piece is formed of a metallic sheath 1 and an inner conducting wire 2 which is disposed and maintained along the axis of the sheath 1. The work-piece 1, 2, is mounted on a vibrator 3 having a frequency-of, for example, 50 cycles per. second, which is shown diagrammatically as a rotor 4 with an-outof-ba'lanceportion 5 and which rests on springs 6 on the ground. The mineral insulating material 7 is fed through the top of the sheath -1 by means of a distributor 8.

Two weights 9, the vertical median section of which has the shape of a triangle, the lower oblique side of which has a slope preferably substantially equal'to the natural conductor 2.

2,718,990 Patented Sept. 27, 1955 angle of repose of the substance 7 (Figure l), have-a semicircular horizontal median section. The two horizontal sections of the weights 9 together occupy the whole section .of the internalpart of the sheath 1 notoccupied bythe It can be seen that the lowerfaces of the Weights9 form an acute angle with the inner conductor 2 and that the tips of the lower faces of .the weights adjacent the sheath 1 are lower than the tips-of'the weights adjacent the conductor 2.

The weights 9 are attached by rods 10, shapedas circular arcs in order to give them more resistance to-bending, to a balance beam 11 at two :points 13 equidistant from the center of oscillation 12 of the balance beam 11. Oscillatory movement is impressed upon-'the'latter'by a transmission represented diagrammaticallyby a connecting rod 14 attached to an eccentric point in a disc 15mttating about its axis.

The assembly consisting of weights 9, rods 10, balance beam 11 and driving mechanism 14 and 15, is suspended from a cable 16 whichpassesover pulleys 17. The cable :16 supports, at the end of its other vertical run, a counterweight 18.

The described device operates as follows:

Under the action of the high frequency impulses communicated to the work-piece 1, .2, andto all'that it contains, the insulating material 7 fed in a regular mannerby the distributor 8 is subjected to a consolidating effect. The mass of the weights 9 exerts a reaction on the material 7 which is thus transformed intoa compact block forminga solid bearing for that weight 9.

During this time, the other weight 9 is progressively lifted by the balance beam 11 and the intermediate'rods 10.

The free space thus formed beneath these weights 9 is progressively filled by the powder which showers-intothe sheath 1.

Aspreviously mentioned, the insulating material is consolidated by the action of the vibrator 3. When the weight 9 under consideration has completed .its upward stroke, it has a sufficiently good support beneath it for the preceding reasoning to be again applicable.

The assembly 9, 10, 11, 14 and 15, therefore'rises gradually, constantly bearing on the compact block of powder which forms progressively beneath it.

As this process continues, the degree of compactness is determined by the reactions of the weights 9 and, therefore, by the mass of the latter, and by the thrust of the assembly 9, 10, 11, 14, 15 which is regulated by the counterweight 18.

When the weights 9 have been lifted up as far as the upper part of the sheath 1, the filling is terminated and the work-piece: sheath 1, conductor '2, insulating material 7, -is ready for the subsequent drawing operation.

In the case of a single conductor 2, the assembly of the weights 9 can also be given a rotary movement about the vertical axis formed by the conductor 2.

Naturally, the present invention is not limited to the process and apparatus described above.

Thus, for example, the apparatus can be used for cables having several inner conductors 2 by simple modification of the section of the weights 3, as can be seen in Figure 3.

It may finally be stated that the invention covers also the use, with or without a jolting device, of a number of weights capable of being displaced one relatively to the other, so as to leave between them at least at-certain instants a space through which the insulating material can .pass beneath the weights.

1. An apparatus for consolidating powderedinsulating material in an electric cable having an external sheath and at least one conductor to be separated from said sheath by said insulating material, comprising, in combination, means for supporting vertically the cable, said supporting means making contact with said cable at the lowermost cross-section thereof; means for imparting vibrations to said supporting means and said cable supported by the same; two weights of triangular cross section adapted to be arranged in said cable alongside each other on opposite sides of said conductor so as to act on separate portions of said powdered insulating material filling said cable; and means for imparting to said weights, respectively, alternative motions out of phase with one another, whereby one of said weights compresses said powdered insulating material in said cable while the other of said weights is ineffective, and vice versa, the lower faces of said weights forming an acute angle with said conductor, the tips of the faces of said weights adjacent said cable being lower than the tips of said weights adjacent said conductor.

2. An apparatus for consolidating powder insulating material in an electric cable having an external sheath and at least one conductor to be separated from said sheath by said insulating material as in claim 1, in which the acute angle formed by said lower faces of said weights and said conductor is substantially equal to the angle of the natural slope of the insulating material to be compressed.

3. An apparatus for consolidating powdered insulating material in an electric cable having an external sheath and at least one conductor to be separated from said sheath by said insulating material, comprising, in combination, means for supporting vertically the cable, said supporting means making contact with said cable at the lowermost cross-section thereof; means for imparting vibrations to said supporting means and said cable supported by the same; two weights of triangular cross section each having a lower face forming an acute angle with a horizontal plane, the tips of the faces of said weights adjacent said cable being lower than the tips of said weights adjacent said conductor, said weights being adapted to be arranged in said cable alongside each other on opposite sides of said conductor so as to act on separate portions of said powdered insulating material filling said cable; and means for imparting to said weights, respectively, alternative motions out of phase with one another, whereby one of said weights compresses said powdered insulating material in said cable while the other of said weights is ineffective, and vice versa.

4. An apparatus for consolidating powdered insulating material in an electric cable having an external sheath and at least one conductor to be separated from said sheath by said insulating material, comprising, in combination, means for supporting vertically the cable, said supporting means making contact with said cable at the lowermost cross-section thereof; means for imparting vibrations to said supporting means and said cable supported by the same; two weights of triangular cross section adapted to be arranged in said cable alongside each other on opposite sides of said conductor so as to act on separate portions of said powdered insulating material filling said cable, each of said two weights having a lower face forming an acute angle with said conductor, the tips of the faces of said weights adjacent said cable being lower than the tips of said weights adjacent said conductor; two rods supporting said weights; and means for driving said rods, said driving means imparting to said rods, respectively, alternative motions out of phase with one another, whereby one of said weights compresses said powdered insulating material in said cable while the other of said weights is ineffective, and vice versa.

5. An apparatus for consolidating powdered insulating material in an electric cable having an external sheath and at least one conductor to be separated from said sheath by said insulating material, comprising, in combination, means for supporting vertically the cable, said supporting means making contact with said cable at the 4 lowermost cross-section thereof; means for imparting vibrations to said supporting means and said cable supported by the same; two weights of triangular cross section adapted to be arranged in said cable alongside each other on opposite sides of said conductor so as to act on separate portions of said powdered insulating material filling said cable, each of said two weights having a lower face forming an acute angle with said conductor, the tips of the faces of said Weights adjacent said cable being lower than the tips of said weights adjacent said conductor; two rods supporting said weights; and means for driving said rods, said driving means imparting to said rods, respectively, alternative motions out of phase with one another, whereby one of said weights compresses said powdered insulating material in said cable while the other of said weights is ineffective, and vice versa, said imparting means including a balance beam having two arms connected, respectively, to said rods, and a motor imparting to said balance beams a rocking motion in alternative opposite directions about the center of said balance beam.

6. An apparatus for consolidating powdered insulating material in an electric cable having an external sheath and at least one conductor to be separated from said sheath by said insulating material, comprising, in combination, means for supporting vertically the cable, said supporting means making contact with said cable at the lowermost cross-section thereof; means for imparting vibrations to said supporting means and said cable supported by the same; two weights of triangular cross section adapted to be arranged in said cable alongside each other on opposite sides of said conductor so as to act on separate portions of said powdered insulating material filling said cable, each of said two weights having a lower face forming an acute angle with said conductor, the tips of the faces of said weights adjacent said cable being lower than the tips of said weights adjacent said conductor; means for imparting to said weights, respectively, alternative motions out of phase with one another, whereby one of said weights compresses said powdered insulating material in said cable while the other of said weights is ineffective, and vice versa; at least one pulley; a cable passing over said pulley and having two ends, one of said ends of said cable being attached to said imparting means; and a counterweight attached to the other end of said cable. 7. An apparatus for consolidating powdered insulating material in an electric cable having an external sheath and at least one conductor to be separated from said sheath by said insulating material, comprising, in combination, means for supporting vertically the cable, said supporting means making contact with said cable at the lowermost cross-section thereof; means for imparting vibrations to said supporting means and said cable supported by the same; two weights of triangular cross section adapted to be arranged in said cable alongside each other on opposite sides of said conductor so as to act on separate portions of said powdered insulating material filling said cable, each of said two weights having a lower face forming an acute angle with said conductor, the tips of the faces of said weights adjacent said cable being lower than the tips of said weights adjacent said conductor; two rods supporting said weights; means for driving said rods, said driving means imparting to said rods, respectively, alternative motions out of phase with one another, whereby one of said weights compresses said powedered insulating material in said cable while the other of said weights is ineffective, and vice versa, said imparting means including a balance beam having two arms connected, respectively, to said rods, and a motor imparting to said balance beam a rocking motion in alternative opposite directions about the center of said balance beam; at least one pulley; a cable passing over said pulley and having two ends, one of said ends of said cable being attached to said imparting means; and a counterweight attached to the other end of said cable.

(References on following page) References Cited in the file of this patent UNITED STATES PATENTS Ayres Feb. 5, 1889 McKibben Feb. 10, 1903 Lightfoot Nov. 16, 1920 6 Marsh Mar. 18, 1924 Marsh Feb. 22, 1927 Hclfrecht Feb. 14, 1933 Abbott May 18, 1943 Griffin June 26, 1945 Stuart July 18, 1950 

